In the manufacture of household paper products such as facial tissue, paper toweling, bath tissue and the like, continual efforts are directed toward improving the perceived softness of the product. In general softness is imparted to the paper web by creping, which serves to rupture fiber-to-fiber bonds within the web and thereby increase bulk and softness. One method of creping such webs, commonly referred to as "microcreping," is described in U.S. Pat. No. 3,260,778 issued July 12, 1966 to Richard R. Walton and entitled "Treatment of Materials." This patent, which is hereby incorporated by reference, describes a method in which the web is supported on the surface of a rotating drum and lengthwise compressed in a treatment cavity defined by the surfaces of the rotating drum, a primary blade which presses the web against the rotating drum, and an inclined rigid retarder blade which retards the forward movement of the web and dislodges the web from the surface of the rotating drum. The treatment cavity prevents the web from buckling beyond the dimensions of the treatment cavity, causing a lengthwise or machine direction compression of the web which results in softening.
However, heretofore a limiting factor of the microcreping process has been the speed in which the process can be operated. Speeds of 1500 feet per minute for a single ply web are generally considered the top speed. For high volume products such as tissues and toweling, this speed limitation has prevented significant commercial use of the process. Therefore there has been a need to improve the speed of the microcreping process without sacrificing the softness and strength of the product.